We've discovered the same problem after upgrading to 7.3.
The problem seems to occur in daypilot-calendar.js. If you have access to the source code, you can fix this manually in daypilot-calendar.src.js line 5674
// belongs here
var belongsHere = false;
if (isResourcesView) {
belongsHere = (col.Value === e.Resource) && !(endTicks <= colStartTicks || startTicks >= colEndTicks);
}
e.Resource should be replaced by e.resource (the JSON returned by the service uses lowercase fields)
Hopefully DayPilot will provide a new release soon that fixes this problem.